1. Field of the Invention
The present invention relates to an electrically-operated air pump suitable for supplying air to the exhaust system of an internal combustion engine.
2. Description of the Relevant Art
Automotive engines often have an air pump for supply of air to the engine exhaust system. The air supports combustion of hydrocarbons and carbon monoxide in the exhaust system to minimize admission of those compounds into the atmosphere.
In the past, such air pumps generally have had a mechanical drive from the engine and accordingly consume engine power during all operating modes. In many applications, however, air is required to support combustion in the exhaust system only during the initial period of engine operation. Thus, in those instances, the air pump has undesirably consumed engine power after the initial period of engine warm-up and, at a time when supplemental air is not required.
Additionally, the traditional engine-driven air pumps require a rigid mounting scheme at the front of the engine which requires a relatively large amount of underhood space. As the space available within vehicle engine compartments is reduced, due to automobile size and styling concerns, it is desirable to reduce the number of engine mounted accessories.